Radio receiving circuits



June 30, 1936. c. c. TAYLOR 2,045,735

RADIO RECEIVING CIRCUITS Filed May 26, 1934 mvENTok v aazhylor Wc ATTORNEY PatentedJune 30, 19 36 I l i 1.

UNITED STATES. PATENT orrics aamo CIRCUITS I. Charles Chance. Taylor, Flushing, N. If assignor to American Telephone and Telegraph Company, a corporation of New York Application May as, 1934, Serial s... 721.191 16 Claims. 178-88) This invention relates to the transmission of polar-relay A so that they are oppoflng, the cursignals over .radio telephone systems or other rent from RR; causing A to operate and the curehannels for the transmission of intelligence and rent from RR: causing A to return to its normal more particularly, to arrangements at the receivor non-operated position. Noise currents e'ntering end for receiving, through heavy static and ing through both bands of filter arrangement 5 fading conditions, signaling pulses for control Fl' Fii tend to balance out'and therefore cause currents, telegraph and teletypewriter transmisno operation'of relay A. There is also a biasin sion or other control or alarm functions. I winding on relay A so energized by the ionic tube As is well known, signal pulses may be sent circuit (to bra-described later) that the biasing over radio circuits by keying the carrier or by current always aids the tone which has operated l0 carrier on-ofl? for control current usage. Like- A,'thereby making fading of the tone less botherwise, use may be made of carrier shift with arw some due to this biasing lock up which holds the rangements' in the radio receiver to produce two relay during any fades occurring after A op- ,voice frequency tones. Similarly. the carrier may crates. A fade which occurs at'the. beginning of be modulated with a single tone or with two a signaL before operation occurs may still, of i5 tones, one for marking, the other for spacingsig course, prevent or delay this operation. Static nals. In accordance with this invention arrangecurrents in order :to: affect operation must be ments are provided whereby this two-tonev or "unbalanced suflicintly when either F1 or E: is single-tone transmission, regardless of how transpresent to overcome the-bias plus the tone output mitted, so long as voice frequency signals are currents.

emitted from the radio receiver, may be received The ionic tube circuit includes two gas-filled with a minimum of interference from static tubes 1T1 morn each having a grid, a cathode crashes and fading. andah anode, the cathode being or the uni-poten- The invention may be more fully and rstood tial type which may be heated by a filament from the following description when read in conlocated in its immediate vicinity. The cathodes 25 nection with the accompanying drawing, Elaine of the two tubes are connected to ground through 1 of which shows acircuit arrangement ior re-' the common resistance. CR1. The plates of the ception of two-tone signals with, static currents twb tubes are connected to the plate battery 7 balanced out and with an ionic tube circuit to through'the upper and lower windings of the relay Ell . reverse biasing current so that the bias aids. the Band through the common resistance PR1. there to,

tone being transmitted and locks the circuit up being resistances PR: and PR3 provided in the against fading of that tone and against any unindividual plate connections. The armature of balance of static currents, and Fig. 2 of which the relay A is arranged so that'when it is on its shows a circuit arrangement for reception of sinupper contact the grid oi the tube IT: will be at 33 gle-tone signals with static currents balanced out ground potential through the resistance GRc, 85 and biasing arrangements which aid the single while the grid of the tube 1T1 will be connected tone when it is present so that deeper fading of the to the potential of its cathode through the resisttone may be tolerated than would otherwise be ance (331. When the armature is on its lower possible. a contact the connections will be reversed, the grid 40 Referring to Fig. 1, R0 designates the output of the tube 1T1 being at ground potential through 40 of a radio receiver, the method of transmission resistance GRz, and the grid of the tube IT: being being such that one or the other of two voice fre connected to the cathode through resistance GRi. quency tones is present in this output. Forillus- The characteristics of the tubes are such that tration I .have taken 935 (F1) and 1105 (F2) when the grid is negati've with respect to the cycles. The tone enters through the input transcathodes-the impedance of the' cathode-plate cirfmrmzri IN and passes through thetwo-stageamcult of the tube will be very high and noplate pl fier. In the output circuit of the second vacucurrent will flow, as very few electronswill be um tube VTz is a double band-pass filter arrangeemitted by the cathode due to the negative field mcnt F1Fz, which also is .the plate battery feed in its vicinity produced by the. grid. When, how- 5 for VT2. This filter arrangement passes the freever, the grid is raised to substantially the cathode qucncy F1 in one band and F2 in the other, and potential, electrons will be emitted freely from feeds the full-wave rectifiers Em and RR: of the cathode thereby ionizing the gas in the'tube which the individual units may be copper-oxide and causing thetube to break down, that is, causor other well known types of rectifiers. The outing the impedance between the plate and filament put currents from the rectifiers are applied to to be lowered with consequent reduction of the 55 plate-cathode drop so that current will flow in the plate-cathode circuit.

the drop through the resistance CR1 may be made about 10 'volts so that the cathode of each tube will be 10 volts above ground. With the armature of the relay A upon its upper contact and the grid of the tube IT: at ground potential, the grid of the tube. IT1 will be about 10 volts negative withrespect to the cathode, thereby substantially preventing electrons from passing from cathode to anode to ionize the tube and break down its impedance. No current will flow through the tube therefore, and the plate of the tube IT: will be about 100 volts above ground, or about volts above the potential of its cathode. No current will flow through the lower winding of the relay B.

'With the armature of the relay A upon its upper contact, the grid of the tube IT1 will not be negative with respect to the cathode, but will be connected directly to the cathode through the resistance GR1, and hence, will be at the cathode potential. Electrons will be emitted by the cathode and the gas in the tube will be ionized so that its impedancewill be lowered. The plate cathode drop will then be about 20 volts so that the plate will be about 30 volts above ground (the drop through CR1 being about 10 volts). Current will flow from the plate battery through the resistance PR1, the upper windings of the relay B, through the resistance PR2 from the plate to the filament of the tube IT1, and through the resistance CR1 to ground. The upper winding of the relay B will therefore be energized to hold its armature against its upper contact.

ound, and the plate of the tube IT: is about volts above ground, there will be about 70 volts difference of potential between the two plates which causes the condenser C1 to be charged up and current to flow through the resistance BB1 and the biasing winding of the relay A, in sucha direction that said winding tends to aid the tone F1 to hold the armature of v the relay A against its upper contact. 1

When the frequency F1 is replaced by the frequency F1, the rectified current through the lower winding of the relay A ceases, and rectified current flows through the upper winding of said relay. This produces a force upon the armature of the relay opposite in direction to that exercised by the biasing winding, and of such strength as to shift the armature of the relay to its lower contact. The grid of the tube IT1 is now isolated from its cathode and is at ground potential, while the grid of the tube IT: is connected over the armature of the relay A and through the resistance GR1 to the cathode of the tube IT1. The grid of the tube IT1, being now substantially at its cathode potential, causes the tube to break down so that its plate-cathode potential will drop to about 20 volts and it's plate will be about 30 volts above ground. The 70 volt charge built up in the condenser C1 now leaks .oiT, lowering for an instant the potential on the plate of the tube IT1 by 70 volts. This makes the Since the plate of the tube IT1 is about so volts above 1 de-ionization, and with its grid now at ground potential through the resistance GRz, the tube IT1 remains de-ionized. Current now flows through the lower winding of relay B operating it to its opposite contact. With IT: ionized 5 and IT1 restored, the potentials at their plates are reversed, that of the plate of IT1 being about 100' volts above ground and that of the plate IT1 being about 30. volts above ground. This causes current to flow through the biasing 10 winding of the relay A in the opposite direction to that previously described so that the bias winding now aids the pull of the upper winding of said relay due to the rectified tone F1.

When the tone F1 ceases and is replaced by the 15 tone F2, the armature of the relay A is shifted to its upper contact by the pull due to the current through the lower winding of the relay thereby isolating the grid of the tube IT: from its cathode and putting it at ground potential, 20 at the same time raising the potential of the grid of the tube IT1 to its cathode potential causing the tube to break down. The plate potential of the tube IT1 now drops from about 100 volts to about 30 volts and the condenser C1, which has 25 in the meantime been charged in the reverse direction to that previously described, now discharges to momentarily lower the potential of 'the'plate of the tube IT: by 70 volts, causing the tube to become de-ionized. The resultant in 30 crease in the impedance of the tube raises its platepotential to about 100 volts above ground and reverses the current through the biasing winding so that the biasing winding now assists the rectified tone F2 to hold the armature of the 35 relay A upon its upper contact.

The values of resistances PR: and PR: and of the capacity C1, may be so chosen that the speed of operation may be as fast as the relays can handle. The value of the biasing current may be adjusted from that which just holds the relay on its contact to somewhat larger values should static unbalances require. The lower value permits signaling with weaker fields or deeper fades where static conditions permit. Larger values may be required for heavy static crashes thereby requiring somewhat higher fields. Consequently, if the adjustment is such as to produce a biasing current suitable for heavy static conditions the permissible fading will not be as great. 50

It is obvious that the operation of the relay B is positive in one direction or the other. Any chattering which may occur on the armature of relay A is not transmitted to the relay B unless the armature of the relay A actually travels to 5 its other contact when, of course, a complete and positive operation of the relay B would occur. The circuit acts therefore, to some extent, as a a pulse corrector and provides satisfactory receptionv of two-tone signals through severe static and fading conditions. I

Consider now Fig. 2 where R0 represents the output of a radio receiver, the method of transmission being such that a tone is received for one signal impulse and no tone for the other." For example, 935 cycles (F1) may be received for a marking pulse and no tone for the spacing-pulse. Static currents are balanced out as in Fig, 1 by the output currents of rectlflers RR1 and RR: being applied to polar relay Aso that they are ,7 opposing; It will be understood, of course, that while the selective device F2 does not receive a tone frequency the average static impulse will have frequencies corresponding to the bands of both selective devices. The two selected static 7 components will be rectified and produce opposite eifects upon the upper and lower windings of the relay A.

The upper winding of relay A is responsive to the tone at 935'cycles to shift the armature to its lower 'or marking contact. The armature is restored to its spacing contact when the marking tone ceases in response to a space signal, by means of the biasing current flowing from battery through the biasing resistance BR! and the biasing winding of the relay A which is the second winding from the top. the marking frequency F1 is received, rectified current from the rectifying arrangement. BB1 must overcome this bias to operate the relay A.

The operation of the ionic tube circuit IT: and IT: and relay B is as explained for Fig. 1. Frequency F1 operates relay A causing IT: to ionize and IT; to become de-ionized. This causes relay B to operate. In addition advantage is taken of voltage drop through a' part of resistance PR: in the plate supply of IT:' to cause a biasing current to flow through one winding of relay A in such a direction as to aid frequency F1. The value of this bias at its maximum adjustment must be sufiiciently less than that bias which holds the relay non-operated so that relay A'wlll be returned to its non-operated position when Irequency F1 is removed. The reason for putting a bias on to aid F1 is that by so doing deeper fading of the tone, ai'ter it has operated A, may be tolerated than would otherwise be possible. This bias may be adjusted up to the maximum mentioned above for ditlerent conditions oi radio field, static and fading. 1 More satisfactory 0p ra-. tion of relay B through all transmission conditions may be obtained than if relay A alone were depended upon for receiving the signals.

What is claimed is:

1. In a receiver, -a relay responsive to received signals, circuits controlled over alternate contacts of the armature of said relay, each circuit including a translating device, means to produce a potential difference between said translating devices under the control of said armature, andmeans to impress said potential difference upon a winding of said relay in such direction as to tend to hold the armature of said relay on the contact upon which it is resting.

2. In a receiver, a relay responsive to received signals, circuits controlled over alternate contacts of the armature of said relay, a translating tube including a cathode and an anode in each of said circuits, means governed by the armature of said relay to control the relative flow. of current in said tubesand thereby produce a difference in potential at the anodes of said tubes, and means to impress said difference in potential upon a winding of said relay in such direction as to tend to hold the armature of said relay on the contact upon which it is resting.

c 3. In a receiver, a relay responsive to received signals, circuits controlled over alternate contacts of "the armature of said relay, a translating tube including a cathode, an anode and a control electrode associated with each of said circuits, means to change the potential of said control electrodes-under the control of the armature oi said relay so that with the armature ,on one contact current will flow in the cathode-anode circuit of one tube and substantially no current will flow .in the cathode-anode circuit of the other Y tube, and with the armature upon the other contact-the conditions will be reversed, and'a wind- 75 ing of said relay having its terminals so assoit is resting.

ciated with the anodes of said tubes that the difference in potential of said anodes will cause current to flow in said winding in such direction as to tend to hold the armature of said relay on the contact upon which it is resting. 5

'4. In a receiver, a relay responsive to received signals, circuits controlled over alternate contacts of the armature of said relay, a gas-filled ionizing tube including a cathode, an anode and a control. electrode associated with each of said 10 circuits, said tubes having such characteristics that when the control'electrode is negative with respect to the cathode substantially no ionization occurs and hence substantially no current flows in the cathode-anode circuit, and when the con-' trol electrode is raised to substantially the cathode pote'ntial ionization takes place so that current flows in the cathode-anode circuit, means whereby when the armature of said relay is ,on one contact the control electrode of one tube is 29 at such potential that ionization occurs and the control electrode of the other tube is at such potential that ionization does not occur, and when the armature is on the other contact the conditions of the tubes are reversed, means associated with the anodes of the tubes to de-ionize the tube previously ionized as the armature shifts from one contact to the other, and a-winding of said relay having its terminals-so associated with the'anodes' of said tubes that the diflerence in potential of said anodes: cause current to How in said winding in such direction as to tend to hold the armature of said relay on the contact upon which 5. In a receiver, a relay responsive to received 35 signals, circuits controlled over alternate contacts of the armature of said relay, each circuit including a. translating device, means to produce a potential. diiference between said translating devices under the control of said armature, a sec-' ond relay having windings differentially connected to said translating devices, and a winding of said first relay having its terminals connected on the output sides of said translating devices whereby the said first relay tends to hold its armature on at least one of its contacts.

6. In a receiver, a relay responsive to receive signals, circuits controlled over alternate contacts oi the armature of said relay, a' translating tube including a cathode and an anode in. each of said circuits, means governed by the-armature of said relay to control the relative flow 01' cur rent in said tubes and thereby produce a diiference in potential at the anodes of said tubes, a second relay having windings diiferentially connected to the cathode-anode circuits of said tubes, and a winding of said first relay having its terminals connected on the output sides of-said' translating device whereby the said first relay tends to hold its armature on at 'leastone of its contacts.

7. In a receiver, a relay responsive to received signals, circuits controlled over atlernate consaid relay so that with the armature 'on one contact. current will flow inthe cathode-anode cir- Y cuit of one tube and substantially no current will flow in the. cathode+anode circuit of the other tube, and with the armature on-the other contact the conditions will be reversed, a. second rela f having windings differentially connected to the cathode-anode circuits of said tubes, and a winding of said first relay having its terminals connected on the output sides of said translating devices whereby the said first relay tends to hold its armature on at least one of its contacts.

8. In a receiver, a relay responsive to received signals, circuits controlled over alternate contacts of the armature of said relay, a gas-filled ionizing tube including a cathode, an anode and a control electrode associated with each of said circuits, said tubes having such characteristics that when the control electrode is negative with respect to the cathode substantially no ionization occurs and hence substantially no current fiows in the cathode-anode circuit, and when the control electrode is raised to substantially the oathode potential ionization takes place so that current flows in the cathode-anode circuit, means whereby when the armature of said relay is on one contact the control electrode of one tube is at such potential that ionization occurs and the control electrode of the other tube is at such potential that ionization does not occur, and when the armature ison the other contact the conditions of the tubes are reversed, means associated with the anodes of the tubes to de-ionize the tube previously ionized as the armature shifts from one contact to the other, a second relay having windings differentially connected to the cathodeanode circuits of said tubes, and a winding of said first relay having its terminals connected on the output sides of said translating devices whereby the said first relay tends to hold its armature on at least one'of its contacts.

9, In a receiver, a selecting 'device for passing two frequency ranges at leastone of which corresponds to a signal into two different circuits, rectifiers in each circuit, a relay differentially connected to said circuits so that interfering disturbances extending over a frequency range wide enough to cover both of said passed ranges will tend to oppose each other in said relay, circuits controlled over alternate contacts of the armature of said relay, each circuit including a translating device, means to produce 'a potential dif ference between said translating devicesunder the control of said armature, and means to impress said potential difierence upon a winding of said relay in such direction as to tend to hold the armature of said relay on the contact 'upon which it is resting.

10. In a receiver, a selecting device for passing two frequency ranges at least one of which corresponds to a signal into two difi'erent circuits, rectifiers in each circuit, a relay differentially connected to said circuits so that interfering disturbances extending over a frequency range wide enough to .cover both of said passed ranges will tend to oppose each other in said relay,

circuits controlled over alternate contacts of the armaturev of said relay, a translating tube including a cathode and an anode in each of said circuits, means governed by the armature of said relay to control the relative flow of current in said tubes and thereby produce a difference in potential at the anodes of said tubes, and means .to impress said difference in potential upon a winding of said relay in such direction as to tend to hold the armature of said relay on the contact upon which it is resting.

11. .In a receiver, aselecting device for passing two frequency ranges at least one of which corresponds to a signal into two different circuits, rectifiers in each circuit, a relay differentially connected to said circuits so that interfering disturbances extending over a frequency range widev enough to cover both of said passed ranges will tend to oppose each other in said relay, circuits controlled over alternate contacts of the armature of said relay, a translating tube including a cathode, an anode and a control electrode associated with each of said circuits, means to change thepotential of said control electrodes under the control of the armature-of said relay so that with the armature on one contact current will flow in the cathode-anode circuit of one tube and substantially no current will flow in the cathode-anode circuit of the other tube, and with the armature on the other contact the conditions will be reversed, and a winding of said relay having its terminals so associated with the anodes of said tubes that the. difference in potential of said anodes will causecurrent to flow in said winding in such direction as to tend to hold the armature of said relay on the contact upon which it, is resting.

12. In a receiver, a selecting device for passing two frequency ranges at least one of which corresponds to a signal into two different circuits, rectifiers in each circuit, a relay differentially connected to said circuits so that interfering disturbances extending over a frequency range wide enoughto cover both of said passed ranges will tend to oppose each other in said relay, circuits controlled over alternate contacts of the arma-.

ture of saidrelay, a gas-filled ionizing tube including a cathode, an anode and a control electrode associated with each of said circuits, said tubes having such characteristics that when the control electrode is negative with respect to the cathode substantially no ionization occurs and hence substantially no current flows in the cathode-anode circuit, and when the control elecelectrode of the other tube is at such potential that ionization does not occur,,and when the armature is on the other contact the conditions of the tube are reversed, means associated with the anodes of the tubes to de-ionize the tube previously ionized as the armature shifts from one contact to the other, and a winding of said relay having its terminals so associated with the anodes of said tubes that the difference inpotential of said anodes will cause current to flow in said winding in such direction as to tend to hold the armature of said relay upon the contact upon which it is resting. v

' 13. In a receiver, a selecting device for passing two frequency ranges at least one of which corresponds to a signal into two different circuits, rectifiers in eachv circuit, a relay difierentially connected to said circuits so that interfering disturbances extending over a frequency range wide enough to cover both of said passed ranges will tend to oppose each other in said relay, circuits controlled over alternate contacts of the armature of said relay, each circuit including a translating device, means to produce a potential difference between said translating devices under the control of said armature, a sec,- ond relay having windings differentially connected to said translating devices, and a winding of said first relay having its terminals connected on the output sides of said translating devices ranges will tend to oppose each other in said relay, circuits controlledover alternate contacts of the armature of said relay, a translating tube including a cathode and an anode in each of said circuits, means governed by the armature of said relay to control the relative fiow of current in said tubes and thereby produce a difference in potential at the anodes of said tubes, a second relay having windings diilerentially connected to the cathode-anode circuits of said tubes, and a winding of said first relay having its terminals connected on the output sides of said translating devices whereby the said first relay tends to holds its armature on at least one of its contacts. 1

15. In a receiver, a selecting device for passing two frequency ranges at least one of which corresponds to a signal into two diiferent circuits, rectifiers in each circuit,'a relay differentially connected to said circuits so that interfering disturbances extending over a frequency range wide enough to cover both said passed ranges will tend to oppose each other in said relay, circuits controlled over alternate contacts of the armature of said relay, 2. translating tube including a cathode, an anode and a control electrode associated with each of said circuits, means to change the potential of said control electrodes under the control of the armature of said relay so that with the armature on one contact current will fiow in the cathode-anode circuit of one tube and substantially no current will fiow in the cathode-anode circuit of the other tube, and with the armature on the other contact the conditions will be reversed, a second relay having windings differentially connected to the cathode-anode circuits of said tubes, and a winding of said first relay having its terminals connected on the output sides of said translating device whereby the said first relay tends to hold its armature on at least one of its contacts.

16. Ina receiver, a selecting device for passing two frequency ranges at least one of which corresponds to a signal into two difierent circuits, rectifiers in each circuit, a relay difierentially connected to said circuits so that interfering disturbances extending over a frequency range wide enough to cover both of said passed ranges will tend to oppose each other in said relay, circuits controlled over alternate contacts of the armature of said relay, a gas-filled ionizing tube including a cathode, an anode and a control electrode associated with each of said circuits, said tubes having such characteristics that when the control electrode is negative with respect to the cathode substantially no ionization occurs and hence substantially no current fiows in the cathode-anode circuit, and when the control electrode is. raised to substantially the.

cathode potential ionization takes place so that current flows in the cathode-anode circuit,means whereby when the armature of said relay is on 'one contact the control electrode of one tube is at such potential that ionization occurs and the control electrode of the other tube is at such potential that ionization does not occur, and 

